Refrigerating apparatus



1935- J L. GIBSON ET AL 2,022,764

REFRIGERATING APPARATUS Original File d Oct. 13, 1931 2 Sheets-Sheet l mx m; 5 1 13 f g Dec. 3, 1935. J L. GIBSON ET AL REFRIGERATING APPARNPUS Original Filed Oct. 13, 1931 2 Sheets-Sheet 2 i a1 E i Patented Dec. 3, 1935 I REFRIGERATING APPARATUS J -Lowell Gibson and Wynne G. Winkler, Dayton, Ohio, assignors, by mesne assignments, to General Motors Corporation, a; corporation of Delaware Application October 13 1931, Serial No. 568,594

Renewed March 17, 1934 13 Claim.

This invention relates to refrigerating apparatus. More particularly it relates to that type of apparatus wherein an object to be cooled is in heat exchange relation with a secondary refrigerating circuit, this circuit, in turn, being cooled by a primary refrigerating circuit. In

of apparatus the danger of mixing the refrigerant of the primary circuit with any substance of the object to be cooled is minimized, since, in case of accidental bursting of any part of the apparatus,

the mixture of refrigerant from the secondaryv system with the substance of the object to be cooled does not set up a chemical reaction which is likely to injure the apparatus. This is so because the refrigerant for the secondary refrigerating circuit can be chosen from a class which is chemically inert to the substances in the object to be cooled, while the refrigerant of the primary refrigerating 20 of the more potentially chemical active type.

Heretofore, particularly when cooling liquids, it has been customary to place a conduitin the liquid refrigerant of the evaporator of a refrigerating system. When the refrigerating system creates an abnormally low temperature in the liquid refrigerant, there is danger that the liquid to be cooled may he accidentally frozen, with the consequent likelihood of bursting the conduit. This mixes together the liquid to be cooled and the refrigerant, and results in damage to the refrigerating system and also to the system with which the liquid conduit is connected. It is one of the objects of this invention to provide a system in which this danger is reduced and in which, nevertheless, a quick and efficient heat transfer is obtained.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein a preferred form of the present invention is clearly shown.

In the drawings:

Fig. 1 is a diagrammatic view of an apparatus embodying my invention;

Fig. 2 is a diagrammatic view similar to Fig. 1 but showing a slightly modified form of the invention; and

Fig. 3 is a diagrammatic view showing the invention applied to a multiple installation.

this type circuit may be, if so desired, I

A refrigerating apparatus embodying features of this invention comprises, in general, a primary refrigerating circuit, generally designated l0, and a secondary refrigerating circuit, generally designated I I. The primary refrigerating circuit may include a refrigerant liquefying unit [2 and an evaporator l3. The secondary refrigerating circuit may include an evaporator I 4 and a condenser IS, the condenser l5 being in heat exchange relation with the evaporator l3. An automatic control l6 governing the operation of 5 the refrigerant liquefying unit I0 is provided, this control l6 being responsive to refrigerant conditions in the secondary refrigerating circuit II.

More specifically, the refrigerant liquefying I unit [2 may be of denser type and includes a compressor l1, driven by a motor I8, and discharging refrigerant into a condenser IS. The refrigerant liquefied in the condenser I9 is stored'in a receiver and is conveyed by the pipe 2| past the automatic expansionvalve 22 to the evaporator l3, from whence it returns by the pipe 23 to the compressor IT. The secondary refrigerating circuit may include a chamber having refrigerant liquid 24 20 to the level indicated, forming the evaporator l4, and this chamber is in communication by the passage 25 with the condenser l5 which surrounds the evaporator l3. [The automatic control l6 includes a bellows 26 incommunication with the evaporator I4 by means of the pipe 21, the bellows 26 operating a snap switch 28 which starts and stops the motor l8.

Liquid to be cooled by the apparatus passes from any suitable source of supply through a 30 conduit 29 submerged in the liquid refrigerant 24 of the evaporator l4 and from thence to a faucet or the like. When the liquid is drawn through the conduit 29 it warms the refrigerant 24 which in turnevaporates and condenses on the surface of the evaporator i3 in the condenser IS. The refrigerant in the evaporator 13 is evaporated and is withdrawn by the come pressor I! which in turn compresses and liquefies the same through the medium of the condenser Ill and recirculates in the evaporator l3. The refrigerant liquefying unit l2, being controlled by control It, operates intermittentlyv in response to the pressure and temperature con-- ditions in the evaporator l4 and maintains'the liquid refrigerant 24 at'a'substantially constant temperature. The valve 22 is of the type which automatically feeds refrigerant to the evaporator'l3 when the evaporator pressure reaches a and is so calibrated that, o

predetermined low level the temperature of the tained sufliciently low to peratures in the liquid 24. V g

The liquid refrigerant .24 preferably is of a composition which does not tend to form corrosive substances when mixed with the liquid to evaporator I3 is main-1' the motor-compressor-conm provide'the desired tembe cooled. Thus where water is the liquid to be cooled, it is convenient to use a halo-fluoro derivative of methane, such as CClzFz, in the evaporator l4, while any of the well-known refrigerants which may or may not be potentially corrosive, and may be chosen more to conform with the requirements of the primary refrigerating circuit than for their chemical relation to the liquid to be cooled. Thus the primary circuit may contain S02. If for any reason the water in the conduit 29 should be frozen sufiiciently to burst the conduit, there would be no danger of damage either to the refrigerating apparatus or to the water system because of mixture of the water with the refrigerant 24, since a mixture of water and CClzFz is not highly corrosive.

In the modification shown in Fig. 2, all of the parts which correspond to those shown in Fig. 1 have been numbered with the same number and with the suffix a. attached. The valve 220., however, has been slightly modified by connecting its bellows to the secondary system through the medium of a conduit 30, to make the valve responsive to refrigerant conditions in the secondary system. The construction of the valve 22a is of such a character that when the temperature of the liquid 24a falls, the valve 22a. is throttled because of the'vapor pressure-tempera,- ture characteristics of the refrigerant liquid 24a and is completely closed when the temperature of the liquid 24a falls below a certain temperature limit. Conversely, when the temperature of the liquid 24a rises, the valve 22a opens. The result of such a. construction is that when a large demand is placed on the refrigerating apparatus by a sustained flow of water through the conduit 29a, then the valve 22a is opened wide and the primary refrigerating circuit operates with a high back pressure. This increases its capacity and provides the necessary refrigeration for the increased demand. The bellows 260. of the control Ilia is connected by the conduit 21a with the secondary refrigerant system Ila. The bellows'26a is so calibrated that it does not stop operation of the unit |2a until the temperature of the evaporator I4ahas been reduced below a predetermined temperature limit-and starts the unit when the temperature is above a predetermined limit.

In the modification shown in Fig. 3 the invention is shown as applied to a multiple installation wherein the refrigerant liquefying unit of the primary refrigerating circuit is connected to a plurality of evaporators. In this case the refrigerant liquefying unit 40 is connected by the liquid refrigerant line 4| with the evaporators 42 and 43. The evaporated refrigerant returns through the line 44 to the liquefying unit 40. One of the evaporators, in this case 42, is in heat exchange relation with the condenser 45 of a secondary refrigerating circuit 46. Thecondenser 45 is connected with an evaporator 41 of the secondary refrigerating circuit similar to the evaporator l4 heretofore described, this evaporator being similarly provided with a conduit 48 for liquid to be cooled. The expansion valve v49 is connected by the conduit 50 with the'refrigerant space of-the secondary system 4B; and the valve 49 is of the same type as the valve 22a heretoforedescribed,andisresponsive to refrigeration demands in the evaporator 41 so that it is throttled with a fall in temperature in the evapporator 41 and is opened with the rise in temperature in evaporator M. The evaporator 43 is of the well-known float controlled inlet valve type now generally used and is fed with liquid refrigerant through the pip 5! which leads to the float conto charge the secondary refrigerating circuit with a certain amount of gas which is non-condensable trolled inlet valve and the evaporated refrigerant returns through the pipe 52 which is connected to the line 44. The evaporator 43 may cool a. brine solution 60 in an ice cream cabinet 6| in which it is intended to maintain lower tempera- 5 tures than those maintained in the evaporator 41. The automatic control 53 for the refrigerant liquefying unit 40 is made responsive to refrigeration demands of one of the evaporators of the primary refrigerating system and also to the demands of the evaporator 41. This is accomplished by providing a bellows 53 which operates a snap switch 54 which in turn starts and stops a motor 55 driving a compressor 56 which in turn discharges refrigerant to the condenser-51 and the receiver 58 in the same manner in which the refrigerant liquefying unit l2 does. The bellows 53 is so calibrated that it does not stop the operation of the unit 40 until the pressurein conduit 44 is below the pressure at which the evaporator 20 42 needs 'to operate to provide refrigeration for the conduit 48. Thebellows 53 is so calibrated also that it starts the liquefying unit 40 when the pressure in the line 44 rises above the pressure necessary to provide the predeterminedup- 25 'per limit of the temperature in the evaporator 42. The stopping of the unit 40 is so calibrated that it will reduce the pressure in the pipe 44 sufficiently to provide the desired low temperature in the evaporator 43. Thus the unit 40 is 30 controlled in response to refrigerant conditions not only within the evaporator 43 but also within the evaporator 41.

The operation of the apparatus herein disclosed is such that the refrigerant liquefying unit of the 35 primary refrigerating circuit starts to operate almost immediately when there is a refrigeration demand upon the evaporator of the secondary system. This is important since it is desirable to release the full power of the liquefying unit as soon so as the demand'occurs, in order that when there is a sustained withdrawal of water, the'liquefying unit is in full operation during the entire time that water is being drawn. This prevents therefrigerant in the secondary system from be- 45 ing warmed up unduly before the liquefying unit starts operation and results in an increased capacity for refrigeration in the apparatus as a whole. In the preferred form of this invention, the secondary refrigerating circuitis charged with a refrigerant which is entirely volatile within the temperature-pressure range of operation of the secondary refrigerating circuit. However, it may be desirable under certain conditions of operation and substantially insoluble, or only slightly soluble,

in the volatile refrigerant. This creates a temperature differential between the evaporators of the primary and secondary circuits respectively.

Many advantages of this invention are obtained even when the refrigerant in the primary refrigcrating circuit is .chemically inert when mixed with the liquid to be cooled.

While the form of embodiment of the invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow..

What is claimed is as follows:

1. Refrigerating apparatus comprising: a primary refrigerant circuit including a refrigerant liquefying unit and an evaporator; a secondary refrigerant circuit including a condenser and evaporator, said condenser being in heat exchange 75 relation to said first named evaporator; a conduit for liquid to be cooled in heat exchange relation to said second named evaporator, and a control governing the operation of said refrigerant liquefying unit responsive to refrigerant pressure within said secondary circuit.

2. Refrigerating apparatus comprising: a primary refrigerant circuit including a refrigerant liquefying unit and an evaporator; a secondary refrigerant circuit including a condenser and evaporator, said condenser being in heat exchange relation to said first named evaporator; a conduit for liquid to be cooled in heat exchange relation to said second named evaporator, and a control governing the operation of said refrigerant liquefying unit responsive to refrigerant conditions within said secondary circuit.

3. Refrigerating apparatus comprising: a primary refrigerating circuit having a motor-compressor-condenser unit and a plurality of evaporators; a secondary refrigerating circuit having a condenser and an evaporator, said condenser being in heat exchange relation with one of said first named evaporators; and an automatic switch governing the operation of said motor-compressor-condenser unit, said switch being responsive to refrigerant pressure of one of said first named evaporators and to refrigeration demands of th evaporator of said secondary system.

4. Refrigerating apparatus comprising: a primary refrigerating circuit having a refrigerant liquefying unit and a plurality of evaporators; a secondary refrigerating circuit having a condenser and an evaporator, said condenser being in heat exchange relation with one of said first named evaporators; and an automatic control governing the operation. of said refrigerant liquefying unit, said control being responsive to refrigerant pressure of one of said first named evaporators and to refrigeration demands of the evaporator of said secondary system.

5. Refrigerating apparatus comprising: a primary refrigerating circuit having a motor-compressor-condenser unit and a plurality of evaporators; a secondary refrigerating circuit having a condenser and an evaporator, said condenser being in heat exchange relation with one of said first named evaporators; and an automatic switch governing the operation of said motor-compressor-condenser unit, said switch being responsive to refrigeration demands of one of said first named evaporators and of the evaporator of said sec-' ondary system.

6. Refrigerating apparatus comprising: a primary refrigerating circuit having a refrigerant liquefying unit and a plurality of evaporators; a

secondary refrigerating circuit having a condenser and an evaporator, said condenser beingin heat exchange relation with one of said first named evaporators; and an automatic control governing the operation of said refrigerant liquefying unit,

said control being responsive to refrigeration demands of one of said first named evaporators and of the evaporator of said secondary system.

7. Refrigerating apparatuscomprising: a primary refrigerating circuit provided with a motor-ccmpressor-condenser unit and an evaporator; a secondary refrigerating circuit including a condenser and an evaporator, said last named condenser being in heat exchange relation with said first named evaporator; an automatic switch governing the operation of said unit, said switch being responsive to pressure within said secondary system.

8. Refrigerating apparatus comprising: a primary refrigerating circuit provided with a refrigerant liquefying unit, and an evaporator; a secondary refrigerating circuit including a condenser and an evaporator, said condenser being in heat exchange relation with said first named evaporator; and an automatic control governing the operation of said refrigerant liquefying unit, said control being responsive to pressure within said secondary system.

9. Refrigerating apparatus comprising: a primary refrigerating circuit provided with a refrigerant liquefying unit, an evaporator and an expansion valve substantially responsive to pressures in said evaporator; a secondary refrigerating circuit including a condenser and an evapo rator, said condenser being in heat exchange relation with said first named evaporator; and an automatic control governing the operation of said refrigerant liquefying unit, said control being responsive to refrigeration demands within said secondary system.

10. Refrigerating apparatus comprising a primary refrigerating circuit including a refrigerant liquefying unitand an evaporator, a secondary refrigerant circuit including a condenser and evaporator, said condenser being in heat exchange relation to said first named evaporator,

change relation to said first named evaporator,

a conduit for liquid to be cooled in heat exchange relation to said second named evaporator, and a control governing the flow of liquid refrigerant into said first named evaporatorin accordance with refrigeration conditions in said second named evaporator.

12. Refrigerating apparatus comprising a primary refrigerating circuit including a refrigerant liquefying unit and an evaporator, a secondary refrigerant circuit including a condenser and evaporator, said condenser being in heat exchange relation to said first named evaporator, means to be cooled in heat exchange relation to said second named evaporator, and a control governing the flow 'of liquid refrigerant into said first named evaporator in accordance with refrigerant pressure in said second named evaporator.

13. Refrigerating apparatus comprising a primary refrigerating circuit'including a refrigerant liquefying unit and an evaporator, a secondary refrigerant circuit including a condenser and evaporator, said condenser being in heat exchange relation to said first named evaporator, means 

